Continuous swimming tanks are known generally. German Patent No. 2,222,594 issued to Hoppe shows a continuous swimming tank. In the tank described therein, water circulates from the front of a swimming area past the swimmer to the rear of the swimming area where it is recalculated through a duct which runs beneath the floor of the swimming area. One set of turning vanes directs the water from the swimming area to the recirculation duct. The water passes over a propeller located in the duct and used for circulation. The second set of turning vanes directs the water from the recirculation duct back into the front of the swimming area.
The swimming area shown in the German '594 patent widens from the front of the tank to the rear of the tank. That is, the cross-sectional area of the swimming area increases from the front to the rear of the tank. This results in velocity variations over the length of the tank. The velocity of the flowing water is greater at the front of the swimming area than it is at the rear of the swimming area. Thus, a swimmer may choose where to swim, according to water velocity. The flow rate of water is constant anywhere in a given cross-section, perpendicular to the direction of water flow. The preceding prior art is incorporated by reference herein.
The problem with such a design is that it requires a large swimming area and thus a large swimming tank. Further, a large motor and great deal of power is required to circulate such a large volume of water.
U.S. Pat. No. 2,035,835 issued to Raber for “Swimming Bath” shows a continuous swimming tank. In this reference, water is circulated either beneath the floor of the swimming area or around the sides of the swimming area. No turning vanes are used to direct the water. The problem with such a tank is that large amounts of turbulence are developed, and loss of water velocity results. Therefore, more power is needed to circulate the water, and swimming comfort is adversely affected by the turbulence. The preceding prior art is incorporated by reference herein.
U.S. Pat. No. 5,044,021 issued to James Murdock for a “Continuous swimming apparatus” discloses and claims swim treadmill which is said to avoid the power and size shortcomings of the prior art by providing a compact swimming apparatus. The apparatus consists essentially of a tank adapted to contain water and having a swimming area within the tank. Water flows through the swimming area from a water entrance end to a water exit end and returns to the water entrance end via a return path. Water circulation means is included in the return path for propelling the water through the return path and through the swimming area. A plurality of vanes is located in the return path to direct the water from the return path to the entrance end of the swimming area and from the exit end of the swimming area to the return path. The vanes help to minimize power losses by minimizing water turbulence. The vanes are spaced in such a way as to create a horizontal velocity gradient across the swimming area whereby water closer to the center of the swimming area has a higher velocity than water near the sides of the swimming area. The preceding prior art is incorporated by reference herein.
Additional prior art of interest include U.S. Pat. No. 1,731,554 issued to M. I. Wheeler for “Swimming Pool” and U.S. Pat. No. 722,232 issued to Hoeglauer for “Bathtub”. The preceding prior art is incorporated by reference herein.